1. Field of the Invention
The invention is directed to a vibration damper, particularly a mono-tube vibration damper wherein a piston carried on a piston rod is axially moveable in a cylinder, the piston dividing the cylinder into two work spaces filled with a work medium.
2. Description of the Related Art
GB 1 447 229 discloses a vibration damper which has, inside the piston rod guide, a flow connection between two work spaces of the cylinder, wherein an adjustable damping valve is arranged inside the flow connection.
Vibration dampers, especially those with an adjustable damping valve, often have very narrow flow connections in which air bubbles can form. In conventional vibration dampers based on the two-tube principle, an axially movable valve ring which is arranged inside the piston rod guide and allows work medium to flow via the connection duct into a compensation space has been used for a considerable time. In this case, trapped air is removed in the region of the piston rod seal. Reference is had, for example, to DE 29 05 928 A1.
It is the object of the present invention to provide a vibration damper, especially a mono-tube vibration damper, with at least one adjustable damping valve in which trapped air inside the vibration damper can be minimized.
According to the invention, this object is met in that the vibration damper has at least one deaerating device at the outer surroundings of the vibration damper for the areas filled with the work medium.
The great advantage of the invention consists in that the trapped air can be completely removed from the vibration damper and need not be collected at a suitable location inside the vibration damper.
In order to keep expenditure on construction as low as possible, the deaeration device is formed by a filler cap or screw closure. The air bubbles form mainly during filling, so that the deaerating device is essentially needed only following filling.
According to a feature of the invention, the deaeration device can be actuated independent from an adjustable damping valve.
In order to enhance its effectiveness, the deaeration device is arranged in the area of the highest point of the regions that are filled with the work medium depending on the installation position of the vibration damper.
The deaeration device is preferably arranged inside a piston rod guide.
Further, it is useful when at least one adjustable damping valve is arranged inside a flow connection between the work spaces and the deaeration device is connected to the flow connection. The air bubbles collect precisely in the relatively small cross sections of the flow connection and can then be removed from the vibration damper by a very short path.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.